Truss-bridge



UNITED STATES PATENT OFFICE.

JOSIAH BROWN, JR., O11` BUFFALO, NEW YORK.

TRUSS-BRIDGE.

Specification of Letters Patent No. 17,722, dated July '7, 1857.

To all 'whom it may concern:

Be it known that I, J osrAH BROWN, Jr., of Bulialo, in the county ofErie and State of New York, have invented a new and useful Improvementin Truss-Bridges; and I do hereby declare that the following is a full,clear, and exact description of the same, reference being had to theaccom anying drawings, forming part of this specilgication, in Whiii-Figure 1, is a side view of a truss frame constructed with my imrovements. Fig. 2, is a vertical section of t e same. Fig. 3, isa planof ditto. Fig. 4, is a side view of an old style of bridge wherein onlythe main braces are shouldered and passed up between the timbers of thechords. Fi 5, is also a side view of another old sty e of bridge whereinthe counter braces only are shouldered and passed up between the timbersof the chords.

The object of my invention is to unite all the timbers of each of thechords in such a manner that they shall become as it were one piece, andconsequently when the strain or weight comes upon the bridge each set ofbraces shall act at one point, and upon all the timbers as united,instead of upon them as separated, whereby all chance of the main bracesacting upon one timber of each of the chords and the counter braces uponthe other timber of each of the same separately or in a manner to twistor rend asunder the said timbers is completely avoided.

The nature of my invention consists in providing each of the main andcounter braces with two gains at top and bottom, and each of the timbersof the chord with a gain at the point where the braces are appliedcorresponding with the gains in the braces and passing the braces thusformed up between the timbers, with the gains of the braces in suchrelation to the gains of the timbers that when the timbers of the chordsare brought together they shall all be combined in such a manner as tobecome as it were only one piece no part of which can be o erated uponor affected independently of t e other by the downward and upwardthrusts common to truss bridges, even if the bolt which passes laterallythrough and intersects each set of braces and the timbers of the chordwere removed, so long as the chords have no lateral lay.

To enable others skilled in the art to make and use my invention, I willproceed to de'- scribe its construction and operation.

A, represents the upper and B the lower chord of the bridge; each iscomposed of four timbers a., a, a, a, as shown in Fig. 2.

O, C, are the main braces, and D the counter braces.

b, l), are the gains cut in the timbers of the upper and lower chords,and c, c, the gains cut in the main and counter braces. The outertimbers of both chords have only one gain cut in them at top and bottom,while the intermediate timbers have each two gains to correspond to thegains ofthe braces which, both main and counter, have each two gains,both at top and bottom. The gains in the braces and in the timbers allmatch when the parts are brought together, as shown in Fig. 2, or sothat the shoulders, formed by the gains on each brace, bear u on twotimbers of the bottom and top c ord, both on the upper and underside ofthe same, and thus by the gains of the three braces and the gains of thetimbers the wholestructure is united together in such a manner as tobecome one piece, as it were, no portion of which will be aifectedindependently of another in a manner to twist or break asunder the same.

E, E, are the bolts which pin the parts laterally together after theyhave been brought together as described.

It should be observed that the bolts E have no other ol'lice to servethan to hold the parts laterally together, and if removed the two chordsand the timbers thereof would still be united and capable of resistingall p vertical strain just as eiiiectually as if the bolts were in.

I am aware that a bridge with the counter braces having gains and passedbetween the timbers of the chords is not new, such an arrangement havingbeen contrived by Geo. W. Thayer in 1848 but in this arrangement, aswill be seen from Fig. 5 of the drawing, the counter braces and mainbraces are not combined so as to act unitedly at one point, and upon allthe timbers of the chords connected or as one piece. The bearing of thecounter braces also extends so far forward or in rear of the main braceswhich abut against vertical posts that a considerable length of leverageis furnished Wherewith to spring or rend asunder the chords when theweight is applied to the bridge. This will be understood by imaginingthe to be the fulcrum of the counter brace, andy the distance from to tobe the levera e of the counter brace wherewith to spring t eintermediate timbers of the chords, as illustrated by the red line.

I am also aware that two braces Awith a l single gain at their upper andlower end crossed diagonally and passed up between two timbers of achord and united by a bolt have been employed in the constructionof abridge by Jas. I-I. Stewart, but in this arrangement the timbers of thechord are not combined with each other by the shoulders formed by thegains and consequently the braces, instead of acting upon the timbers ofthe chord as united in one piece, they act luplln the timbers asseparated, and thus e one forces the other trated by the red and blueulls, as illusnes in Fig. 4c,

What I do claim as my invention7 and desire to secure by Letters Patent,is*

Providing each of the main and counter b races with two gains at top andbottom, and each of the timbers of the chord with a gain at the pointwhere the braces are a plied corresponding with the gains in the braces,and passing the braces thus formed, up between the timbers, with thegains of the braces in such relation to the gains ofthe timbers thatwhenthe timbers of the chords are brought together they are combined andbecome, as it were, only one piece, no part of which can be operatedupon or affected independently of the other by the downward and upwardthrusts common to truss bridges, even if the bolt which passes laterallythrough and intersects each set of braces and the timbers of the chordwere removed, substantially as and for the purposes herein set forth.

JosrAH BROWN, JR.

Witnesses:

B. W. FENWIOK, GOODWIN Y. AT LEE.

